Apparatus for indicating and controlling the amount of strip in looper pits



Dec. 29, 1942. G. H. RENDEL 2,306,750

APPARATUS FOR INDICATING AND CONTROLLING THE AMOUNT OF STRIP IN LOOPERPITS Filed May 9, 1940 3 Sheets-Sheet l [mania]? 650/965 H BEA/05L,

Dec. 29, 1942. G. H. RENDEL 2,306,750

' APPARATUS FOR INDIGATING AND CONTROLLING THE AMOUNT OF STRIP IN LOOPERPI'I'S Filed May 9, 1940 3 Sheets-Sheet 2 6505 5 H Fax 05L,

[mania]? Patented Dec. 29, 1942 -APPARATUS FOR INDICATING AND CON-TROLLING THE AMOUNT OF STRIP IN LOOPEB- PITS George H. Rendel, Gary,Ind.

Application May 9, 1940, Serial No. 334,259

4 Claims.

This invention relates to improvements in means for indicating theamount of slack strip at all times while the strip is traveling betweenfixed stations. Although not limited thereto, the invention ispeculiarly well suited for use in continuous sheet and strip mills whichare frequently equipped with a looper pit adapted to accommodate atraveling loop of material so as to provide sufllcient slack to permitcertain stands of tandem mill to withdraw strip from the pit while thefeedin rolls remain at rest, so as to permit the trailing end of onestrip of material to be welded or otherwise united to the leading end ofthe strip from a supply reel.

matic illustration of component parts of the approved mechanism;

Flgure 4 is a detailed elevation oi. a counting mechanism equippedwithcams and circuit-controlling devices embodying features essential tothe combination herein claimed, and v Figure 5 is a sectional view online V-V of Figure 4.

Referring in detail to the drawings, the numeral In represents a looperpit which is adapted to accommodate a traveling loop of slack materialsuch as that indicated at L. The material is fed into the looper pit byfeed-in pinch rolls l2-l2 located at one end of the looper pit.Similarly the material is fed out of the pit by the mill rolls M-llformingpart of a tandem mill including roll stands I8 and I8 equippedwith rolls of conventional type.

The material fed to the looper pit-comes, :tor

example, from arollstand 20. In the normal operation oi continuous sheetor strip mills, it is the practice to weld the trailing end 22 to theleading end 24 from time to time. For this pur pose, the conventionaltype of welder shown at flisutilized; v p

Since the rolls [2 must be stopped during the welding operation and itis normally desired/not to stop the operation of rolls l4, it isessential that a generous supply of slack strip be present in the looperpit III at all times.

One of the chief features of the present invention is the provision ofimproved means for visually indicating at all.

slack strip is automatically maintained in the looper pit, and toprovide means for stopping the driving motor of the rolls H in the eventthe amount of slack in the looper pit reaches a predetermined minimum.

The means hereinafter described in detail includes, in combination withthe feed-in and feedout rolls and i4, between which a movingloop ofslack strip is adapted to accumulate as the strip is traveling throughroll stands, respective actuating means, each driven at a rateproportional to the peripheral speed of aroll of each of said stands, adifferential mechanism actuated by the joint operation of said twoactuating means, and an indicating device responsive to saiddiil'erential means for showing at all times the length of travelingloop of slack strip between the said spaced roll stands.

The respective actuating means in the embodiment of the inventionillustrated comprises Selsyn transmitters I23 and I 4s. The transmitterl2s is driven at a rate of speed proportional to the peripheral speed towhich the rolls I2 feedthe strip into the looper pit l0, and similarlythe transmitter s is driven at a speed proportional to the peripheralspeed at which the strip is fed out of the looper pit. These two Selsyntransmitters are electrically connected, as shown in the diagram, Figure3, with a differential Selsyn receiver R. The differential Selsyntransmitter rotates the shaft 21 of a counter, the power beingtransmitted through a shaft 28 of the transmitter through worm gearing30 and 32.

The counter illustrated is of asomewhat con-.

Conventional mutilated gears, such as thoseshown at u and t, areeffective to transmit movement from the units dial to the tens dial andfrom the tens dial to the hundredsdial, said units dial U, while eachfoot of strip material leaving the pit will be effective to reverse thedifferential receiver R and has the efiect of subtracting one unit fromthe counter. Therefore it is apparent that if the lineal speed of thestrip entering and leaving the pit is equal, the counter will remainstationary. If the entrance speed is greater than the exit speed, thecounter will rotate forward and thus at all times register theaccumulated amount of slack strip in the pit. Then, when the stripentering the pit is slowed down or stopped, while the strip leaving thepit continues inmotion, the counter will be caused to rotate in areversemanner and will thus indicate the amount of slack strip left in the pit.Thus, the numbers on the counter dials U, T and H visually indicate atall times the amount of strip stored in the looper pit.

The hundreds dial carries a cam 11. which is adapted to control asswitch contact In. The

tens dial carries a cam t which is adapted to As there shown,'each camis slotted as indicated at 34 so as to be adjustably secured by means ofa suitable screw. 36. Each cam contains a dwell portion 38 substantiallyconcentric with the axis of rotation of the dials, and each includes anactive rise portion All which is designed to be positioned opposite aselected digit on the dial. As thus arranged, the several cams can beset in a predetermined manner so as to eflect an automatic controlhereinafter described, whereby a determined amount of slack strip can beautomatically maintained in the looper pit. These cams are alsoeilective to control the operation of respective controllers 4 2 and ll,which in turn govern the operation of respective motors 4i and 48,driving the feed-in rolls l2 and feed-out rolls it through suitable gearreduction transmission mechanism of conventional form.

There is also provided an alarm 50 whose operation is controlled by thecounter cams so as to warn the operator when the supply of slackmaterial in the looper pit has been depleted to an unsafe amount.

When initially startingthe apparatus, after threading a new stripthrough the looper pit II, the counter can be set to zero by operating apush button 52 which controls the circuit of a relay coil 54 whichcloses the circuit across contacts 56, including a counter-resettingmotor 58. By so resetting the counter to zero after initially threadingthe strip through the pit, compensation is made for the distance betweenthe ends of the looper pit.

The mode of operation of the apparatus will be of a specific example.In'practice, it has been determined that under certain operatingconditions it is advisable to maintain 570 feet of slack strip in thelooper'pit. This will give adequate time to weld the trailing end of anoutgoing strip to the entering end of an incoming strip without thenecessity of stopping the rolls ll or other rolls of the stands l6 andI8 of a continuous mill. When the aniount of slack strip is so depletedas to contain, for example, only 80 feet, the danger zone is beingreached. Accordingly, in the example of operation herein described, thecams u, t, h and h are so set that their active rise portions arelocated in radial alignment with the appropriate numerals on the dials,as will more specifically appear as the description proceeds.

The rise -on cam h of the hundreds dial is aligned with the numeral 5 ofthe dial. As so arranged, switch in is closed when the numeral 5 readilyunderstood by the following description comes to a predeterminedoperative position, and is open at all other times.

The rise portion on cam t is arranged to be aligned with the numerals 7and 8 of the tens dial. As thus arranged, the switch It is closed whenthe numerals 7 and 8 come to an operative position, and is open at allother positions.

The rise on hundreds cam his aligned with numeral 0 on the hundredsdial. Thus the switch 3h is closed when the numeral 0 on the hundredsdial comes to operative position, and is open at all other points.

The rise on cam u is located in line with numeral 0 on the units dial.Thus the switch lu will be open when the units dial reaches the 0position, and will be closed at all other points.

The cam settings referred to in detail correspond to the number 510,representing the illustractive desirable number of feet of slack to bemaintained in the looper pit, and 80, representing the illustrativeminimum safe amount of slack.

In a typical operation, assume that the new strip has been threadedthrough the looper pit and the dial counter will have been'reset, thuscompensating for the distance between the ends of the looper pit whenthe push button 52 is pressed. The operation of the push button iseilfective to energize the coil 54 of relay D. Thisuntil the cams on allthe dials register zero, at

which time the holding circuit is broken by reason of the switch inbeing opened by the cam U, H being opened by contacts on cam TI and thecontacts on relay C opened due to contact In closing, thus energizingcoil 88. After such resetting of the counter to zero position, theapparatus is in readiness for operation, and as the 1 moving strip isaccumulated in the pit the dial counter advances. When the numeral 5 onthe hundreds dial H reaches a determined reading position, switch incloses, thus energizing the coil 62 of relay A. As the strip continuesto advance, the numeral I on tens dial T comes to operative readingposition, whereupon switch It closes, thus energizing the coil 64orrelay 'B. The energization of the coil 52 of relay A was effective toclose the circuit across contacts N of said relay through the controller42 which in turn controls the circuit to the pinch roll drive motor 46,and thus causes the pinch roll motor to operate at a speed which willdeliver strip to the looper pit so as to maintain a slack supply of 570feet of such strip therein.

To protect the equipment from damage such as would be likely to occur ifthe requisite amount of slack was not maintained in a looper pit, theapparatus in the example assumed is arranged to sound an alarm and slowdown the mill when the amount of strip is reduced to 80 feet. This isaccomplished as follows: As the stored strip in the looper pit becomesdepleted and'the hundreds dial reaches 0, the cam 11. thereof closesswitch 3h, thus energizing the coil 68 of the relay C. As the storedstrip in the looper pit becomes further depleted, so asto turn tonumeral 8 on the tens dial T to operative position, the cam t will closethe switch 2t and thus energize the coil 64 of the relay B. Uponenergization of relay B, the circuit will be closed across contacts 10thereof so as to complete a circuit through the alarm 50, and thecontroller 44 which governs the operation of the motor 48. Thus when theamount of slack strip becomes so depleted that there is only 80 feetthereof in the looper pit, a warning signal will be given and the millwill be slowed down by operation of the controller 44. If desired, thiscontroller can be soarranged as to stop the operation of the mill drivemotor 48.

From the foregoing, it is apparent that the combination of cooperatingdevices provides a safeguard which will automatically maintain apredetermined amount of slack strip in the looper pit sufficient to giveample time to efiect the joining of portions of the strip withoutshutting down the mill operating on other portions of the strip. Also,in the event that an insufiicient amount of slack strip is present,ample warning will be given and the feeding-out of the strip from thelooper pit will be automatically interrupted.

While I have described quite specifically the embodiment of theinvention herein illustrated. it is to be understood that variouschanges in arrangement and modifications of details may be made withoutdeparture from the scope of my invention as defined in the appendedclaims.

I claim:

1. The combination with two spaced roll stands between which a. movingloop of slack rolled strip is adapted to accumulate, of respectiveactuating means, each driven at a rate proportional to the peripheralspeed of a roll of each of said stands; diiferential means actuated bythe joint operation of said two actuating means; a counter mechanismactuated by said differential means indicating the length of said loopof slack strip; respective controllers governing the lineal speed atwhich the strip enters and leaves the looped portion thereof, andswitches actuated by said counter mechanism located in circuits ofelectrical devices which control the operation of said controllers. I

2. The combination with two spaced roll stands between which a movingloop of'slack rolled strip is adapted to accumulate. of respectiveactuating means, each driven at a rate proportional to the peripheralspeed of a roll of each of said stands; differential means actuated bythe joint operation of said two actuating means; mechanism actuated bysaid differential means indicating the length of said loop of slackstrip, said mechanism including cams and switches actuated by said cams;electrical devices in circuits with said switches; and respectivecontrollers responsive to said electrical devices, said controllersgoverning the respective lineal speeds at which the strip strip isadapted to accumulate, of respective actuating means, each driven at arate proportional to the peripheral speed of a roll of each of saidstands; differential means actuated by the joint operation of said twoactuating means; counter mechanism actuated by said diflferential meansindicating the length of said loop of slack strip, said countermechanism including cams, switches actuated by said cams, respectiveelectrical circuits controlled by said switches, electromagnetic meansin each of said circuits, respective supplemental circuits under controlof said electromagnetic means, and respective controllers in thesupplemental circuits effective to govern the lineal speed at which thestrip enters and leaves the looped portion thereof.

4. The combination with two spaced roll stands between which a loop ofslack rolled strip is adapted to accumulate, of a respective Selsyntransmitter driven by a respective roll of each of said stands; a singlediflerential Selsyn receiver actuated by the joint operation of bothsaid transmitters; a counter mechanism having respective dialscorresponding to units, tens, hundreds, etc., driven by said receiverfor indicating the length of said loop of slack strip; respective switchcontacts controlling circuits of respective electrical devices eifectiveto give an alarm and slow down or stop the mill to prevent damage to therolling equipment in the event that the amount of stored strip materialbecomes exhausted, and respective means moving with said dials foractuating said switch contacts.

GEORGE H. RENDEL.

